Friday, March 16, 2007

And with the return of the geese, it's official: Winter is now over. It took its sweet time coming, arriving in mid January, and it's ended in mid March. Only two months. Did I mention that this is Canada?

It was only a month ago that we were freezing our asses off, and people were making cracks about Global Warming. To which I generally replied, "Yeah! How dare it be cold in January! In Canada no less!"

This is one of the problems with getting people to accept that Global Warming is happening: Winter still comes. It's shorter and less intense, but there's still a winter, and those two (down from five) months confirm in everyone's mind that yes, things are alright, it still gets cold. This is likely a form of confirmation bias at work, with people picking and choosing the evidence they look at to fit what they want to believe. In cases like this, they can somehow manage to draw exactly the wrong conclusion from the evidence.

Here's the lowdown: Global Warming is a rise in the average global temperature at a given point in the year over time. In addition to the average rising, the complicated mechanisms of weather systems result in certain areas getting significantly hotter than the average rise, some areas getting colder, some areas getting drier, some getting wetter, and some seeing almost no change. What happened here was that winter was not only shortened from around five months to around two, but it was much less intense than in past years.

So, is that evidence of Global Warming? Yup. Does it prove it? Not by a long shot. In order to "prove" it (to the extent that any phenomenon can be proven), you have to look at trends the world over. When you look at the average temperatures for the past century, there's a very definite rise.

If you look at the CO2 levels in the atmosphere, there's an even more definite rise, and those levels are predicted to explode in the next few years. Historically, there's a very strong positive correlation between CO2 levels and global average temperature. We should be careful though, as correlation doesn't imply causation. It could be temperature causing the CO2 levels, CO2 levels causing the temperature, or something else causing both.

So, to test this, Climatologists came up with some testable predictions about what would happen if the rising CO2 levels do indeed cause rising global temperature. The obvious prediction is that we'll measure the average temperature as rising, likely to historically unprecendented levels (to match the unprecendented levels of CO2). It has indeed been rising, though we haven't seen the huge spike yet (likely due to lag time, as the sun's energy builds up, getting trapped in the atmosphere slowly).

There are tons of other effects of Global Warming that we've seen as well: Ice shelves in Antarctica are breaking up. Glaciers are receding. Lakes are drying up. Sea level is rising (from the melted ice). So far, none of these pose much threat (except for some of the lakes which have dried up, causing droughts in certain areas), but there's one big threat looming right in our backyard: Greenland.

The ice sheets covering Greenland are land-bound. Unlike floating ice, if land-bound ice melts, it will result in a rise of the sea level. And there's a lot of it to worry about. So much, in fact, that if it melts, thousands of coastal cities, including a number of metropolises, will be flooded. But we don't have much to worry about, right? The ice is melting slowly, so it won't be a problem nearly anytime soon, and we can react slowly, right?

Wrong. Greenland has one notable feature which makes it particularly menacing: The ice sheets are held in by a single, large plug. If that plug were to break, the water would no longer be locked on it and would burst out rapidly (on a global timescale, that is. We might get a couple of years at the outside to react, but judging by the reconstruction of New Orleans, that's still too fast for our government to react). And you know what? We've already observed the plug to be shrinking. The clock's counting down.

There's still a lot of resistance to the idea of Global Warming from people who have it in their best interests that it not be true, or at least that people not believe it to be true. For the most part, their arguments don't hold up. I'll be returning to this subject shortly to go over some of the most common objections to Global Warming.

4 comments:

I'll be returning to this subject shortly to go over some of the most common objections to Global Warming.

Good to hear. One thing I heard a while back you may want to address:

Allegedly temperature increases cause CO2 to bubble out of the ocean, which is the cause of the correlation, rather than CO2 trapping heat.

During my initial plunge into active skepticism, I spent a little time trying to learn a little more about GW, and that particular objection stuck into my mind, since it fits what I know of chemistry, and I know anecdotally that warm soft drinks fizz up more than cold ones.

Another thing you may want to talk about: The role of water vapor, which is supposed to be the primary greenhouse gas, at least according to one dissenter/denier/whatever.

It was only a month ago that we were freezing our asses off, and people were making cracks about Global Warming. To which I generally replied, "Yeah! How dare it be cold in January! In Canada no less!"

I like that one; I'll have to remember it next year. Guelph here gets pretty much exactly the same weather (and climate) as does Waterloo; that's where you are, if I remember earlier posts correctly.

The sea-level rise caused by Greenland's plug melting is indeed a worry. Was it on this blog that I mentioned I've seen estimates of 5+ meters rise from thermal expansion alone? I know you're going to talk about this more, and I eagerly await.

Another thing that bugs me when people half-jokingly-dissent is their terrible memory. Yes, it was frickin' cold here mid-February - but it was positively balmy on January 7. How hard is it to remember the weather of four or six weeks previously?

...reconstruction of New Orleans, that's still too fast for our government to react...

Um, sorry to get all hyper-sensitive-Canadian on you, but whose government, exactly, are you describing?

Ah yes, I am in Waterloo right now, but I currently spend my summers in the States (and I lived there exclusively for over a decade). The result is that I tend to think of myself as being part of both countries (I would have dual-citizenship by now if it weren't for some ridiculous bureaucratic red tape that caused me to spend my first 11 years in America without a Green Card as a "visitor.")

And yes, you also mentioned thermal expansion here, and that's one point I intend to get at. Same with the stuff BD mentioned. I'm still working on the post, so if anyone has anything else they'd like me to hit, there's still time.

Sorry for the irrelevant comment but I couldn't find an email address. Anyway, I’ve tagged you as a Thinking Blogger(http://pillowbook.co.uk/archives/443). If you’re interested in carrying on the meme there are three requirements:

1. If, and only if, you get tagged, write a post with links to 5 blogs that make you think.

2. Link to this post(http://www.thethinkingblog.com/2007/02/thinking-blogger-awards_11.html) so that people can easily find the exact origin of the meme.

3. Optional: Proudly display the ‘Thinking Blogger Award’ with a link to the post that you wrote.